Clip for assembling battery modules

Abstract

The invention relates to a connecting piece (1) for assembling two battery modules (2-1, 2-2), said connecting piece comprising: - a first portion (3) able to be inserted into a notch (4-1) of a first holding element (5-1) of a first plurality of electrochemical elements (6-1) forming part of a first battery module (2-1), and - a second portion (7) able to be inserted into a notch (4-2) of a second holding element (5-2) of a second plurality of electrochemical elements (6-2) forming part of a second battery module (2-2), the first portion and the second portion having different dimensions, such that the first portion is not adapted to be inserted into the notch of the second holding element and / or the second portion is not adapted to be inserted into the notch of the first holding element, - a means (8) for preventing the removal of the connecting piece after it has been inserted into a notch of one of the two holding elements.

Description

Description Title: Clip for assembling battery modules Technical field of the invention

[0001] The technical field of the present invention is that of battery module assembly devices. Context of the invention

[0002] A battery module, also referred to as a module hereafter, consists of several electrochemical cells connected together. Connecting these cells in series increases the battery module's voltage. Connecting them in parallel increases its capacity. The cells are held together within the module by one or more retaining devices, also known as clamps or flanges.

[0003] Several modules can be connected together in series and / or parallel, thus achieving the voltage and current levels required to power an electrical device. All the interconnected modules together form a battery. To maximize the battery's energy density, the modules are generally placed side-by-side.

[0004] Document FR-A-2 562 170 describes a connecting bracket designed to mechanically join two modular elements. One wall of one modular element is positioned opposite the other wall, with one of these walls having an electrical connector intended to be connected to a complementary connector located on the other wall. This bracket has two identical arms that are completely fixed to each other. The arms have the same shape and dimensions. They are designed to be inserted into two identical recesses in the walls of the two modular elements. This type of bracket does not allow an operator to properly orient the modular elements. Furthermore, if the fit between the two modular elements is not perfect, sometimes due to variations in the dimensions of the modular elements, mechanical stresses may occur on the bracket.Since an electrical connection is made between the two modular elements, any play between them is unacceptable as it would compromise the quality of the electrical connection. Finally, this type of jumper can be easily removed from the recesses. In fact, an operator can remove it by hand. The rider is slid along the recess. Therefore, there is a risk that one of the two modular elements could slide downwards and become completely detached from the other modular element.

[0005] We are therefore looking for a connecting piece that can simultaneously: - mechanically connect two battery modules; - to help an operator easily find the predefined orientation of the two battery modules to be electrically connected, in order to prevent, precisely by effect "poka-yoke" via a simple keying system, to prevent unwanted or dangerous electrical connections from being made; - be used to assemble a plurality of modules even when the distance between two battery modules to be joined varies slightly and when there is a slight difference in height between these two modules; - not to disengage spontaneously from a flange, except by using a tool to pierce through the connecting piece.

[0006] Preferably, the connecting piece should allow the assembly of flanges whose outer surface is free of protrusions. For example, the aim is to use flanges whose lateral surface lacks a dovetail joint.

[0007] Preferably, the connecting piece should serve as a fixing point for one or more electrical wires. Summary of the invention

[0008] The present invention overcomes the aforementioned drawbacks by proposing a connecting piece for assembling two battery modules, said connecting piece comprising: - a first portion suitable for fitting into a notch of a first retaining element of a first plurality of electrochemical elements forming part of a first battery module and - a second portion suitable for fitting into a notch of a second retaining element of a second plurality of electrochemical elements forming part of a second battery module, the first portion and the second portion having different dimensions, such that the first portion is not suitable for fitting into the notch of the second retaining element and / or the second portion is not suitable for fitting into the notch of the first retaining element, - a means to prevent the removal of the connecting piece after its insertion into a notch of one of the two retaining elements.

[0009] According to one embodiment, the connecting piece is made of a non-current conductive material, such as plastic.

[0010] According to one embodiment, the first portion comprises a hand-flexible part and a hand-inflexible part, the hand-flexible part and the hand-inflexible part form respectively a first and a second branch, the first and second branches being at least partially disjointed, thus allowing a deformation of the hand-flexible part relative to the hand-inflexible part.

[0011] According to one embodiment, the material constituting the connecting piece has a flexural strength at the elastic limit at 23°C according to the ISO standard ranging from 125 to 315 MPa.

[0012] According to one embodiment, a cross-section of the first portion is circular or semi-circular or oval or semi-oval in shape and a cross-section of the second portion is T-shaped.

[0013] According to one embodiment, a free end of the flexible hand part is beveled.

[0014] According to one embodiment, the means to prevent the removal of the connecting piece is a lug located on the flexible part by hand, adapted to snap against a shoulder of one of the retaining elements.

[0015] The invention also relates to an assembly comprising: - a first battery module equipped with at least one first retaining element used to hold a first plurality of electrochemical elements and a second battery module equipped with at least one second retaining element used to hold a second plurality of electrochemical elements, - a connecting piece as described above, assembling the first retaining element with the second retaining element, the first portion fitting into a notch of the first retaining element and the second portion fitting into a notch of the second retaining element, the first portion being configured so that it cannot fit into the notch of the second retaining element and / or the second portion being configured so that it cannot fit into the notch of the first retaining element, play being present between the first or second portion of the connecting piece and the notch into which the first or second portion fits, this play allowing a movement of one of the two battery modules relative to the other, in the three dimensions of space.

[0016] According to one embodiment, the clearance is at least 0.15 mm and less than 1 mm in each of the three dimensions of space.

[0017] According to one embodiment, the notch of the first retaining element has at least one different dimension from the notch of the second retaining element.

[0018] According to one embodiment, the notch of the first retaining element and the notch of the second retaining element extend along the longitudinal direction of the electrochemical elements, the shape of the cross-section of the notch of the first retaining element being different from the shape of the cross-section of the notch of the second retaining element.

[0019] According to one embodiment, the cross-section of the notch of the first retaining element has a circular or semi-circular or oval or semi-oval shape and the cross-section of the notch of the second retaining element is T-shaped.

[0020] According to one embodiment, - the first and second retaining elements cover a first end of the first plurality and the second plurality of electrochemical elements respectively, - the first connecting piece links the first and second retaining elements located at the same first end of the electrochemical elements, the assembly further comprising: - a first and a second end-supporting element covering the opposite end of the first and second plurality of electrochemical elements respectively, - a second connecting piece linking the first and second retaining element of the second end, the second connecting piece being as described above.

[0021] According to one embodiment, the first and second connecting piece each have a heel preventing the separation of the first and second battery modules.

[0022] According to one embodiment, the first and second battery modules each contain four electrochemical elements, the retaining elements being square in shape, possibly with rounded corners, the four sides of the square each receiving a notch.

[0023] According to one embodiment, two notches located on two opposite sides of the square have different dimensions and shapes.

[0024] Finally, the invention also relates to a battery comprising at least one set as described above.

[0025] The connecting piece is referred to hereafter as a clip. The retaining element is referred to hereafter as a flange. Brief description of the figures

[0026] Embodiments of the invention are described below in more detail with reference to the attached figures.

[0027] [Fig. 1] is a front view of the clip according to the invention.

[0028] [Fig. 2] is a bottom view of the clip in Figure 1. The cross-section of the first portion of the clip is circular. The cross-section of the second portion of the clip is T-shaped.

[0029] [Fig.3] is a bottom view of the assembly area between two modules. It shows in particular the play in a horizontal plane between one of the two portions of the clip (the one shaped like "T") and the notch in which this portion is inserted.

[0030] [Fig.4] is a bottom view of two modules assembled by the clip according to the invention. It shows in particular that the cross-sections of the notches made on two opposite edges of a flange are different.

[0031] [Fig.5a] shows a longitudinal sectional view of the clip assembling two flanges arranged on the upper end of two modules.

[0032] [Fig. 5b] shows a longitudinal cross-sectional view of a clip joining two flanges positioned on the lower end of two modules. Figures 5a and 5b show the presence of a gap between the clip's heel and the inner wall of the flange, allowing the left module to move slightly in the vertical direction.

[0033] [Fig.6] shows a longitudinal sectional view of two modules assembled using a first clip connecting two flanges located on the upper end of two modules and a second clip connecting two flanges located on the lower end of the two modules.

[0034] [Fig.7] is a perspective view of an assembly of two modules. These were assembled using a first clip connecting two flanges located on the upper end of the two modules and a second clip connecting two flanges located on the lower end of the two modules.

[0035] [Fig. 8] is a perspective view of an assembly of three modules. A third module has been added to the two modules in Figure 7. Figure 8 shows, in particular, the addition of clips in the notches of the flanges located on the lower end of the second and third modules.

[0036] [Fig.9] is a perspective view of an assembly in which a 4 ème module is attached to the three modules in figure 8.

[0037] [Fig. 10] is a perspective view of an assembly of four modules. It shows, in particular, the installation of two clips on the upper flange of the 4 ème module.

[0038] [Fig. 11] is a perspective view showing the assembly of the four modules of the figure 10 after all clips have been placed on the upper flanges of the modules. Description of the embodiments of the invention Video description:

[0039] The clip will be described in relation to Figures 1 and 3. The clip (1) typically includes a heel (200, 201) from which extend: - a first portion (3) intended to fit into a notch (4-1) of a first flange (5-1) of a first plurality of electrochemical elements forming part of a first battery module and - a second portion (7) intended to fit into a notch (4-2) of a second flange (5-2) of a second plurality of electrochemical elements forming part of a second battery module. The first and second portions of the clip extend in a direction perpendicular to the longitudinal axis of the heel. They are substantially parallel to each other and are joined together along their entire length.

[0040] The first portion (3) comprises a flexible part (3a) and a non-flexible part (3b) attached to the second portion (7) of the clip. "Flexible" here means "flexible by hand." The flexible part (3a) and the non-flexible part (3b) form two partially separated arms. The fact that the two arms are only partially connected allows the arm (3a) to have some flexibility relative to the non-flexible arm (3b). Furthermore, the flexible arm (3a) is much longer than it is thick, which contributes to its elastic deformation when the clip is inserted into the flange. It is both arms (3a, 3b) of the first portion (3) of the clip that fit into the notch (4-1) of the first flange (5-1) of the first plurality of electrochemical elements, and not just the flexible arm (3a) of the first portion.

[0041] The heel, the first and second portions of the clip are preferably made by molding a plastic material. It is also possible, although less preferred, to weld or glue the first portion, the second portion, and the heel. A plastic material is better suited than a metallic material due to its electrical insulating properties. Indeed, the clip does not participate in the electrical connection between two modules but only in their mechanical assembly. Suitable plastic materials for manufacturing the clip include: - polyetheretherketones, such as Victrex® PEEK 150G, - polyamide-imides, such as Torlon® 5030, - phenylene polysulfides, such as Ryton® R-4 and Techtron® HPV, - polyamides (Nylon®), - polyethylene, polypropylene and their copolymers, although these polymers have less good mechanical properties than the other polymers mentioned. Preferably, the plastic material is a polyetheretherketone (PEEK), such as Victrex® PEEK 150G. Elastomers are less suitable as a constituent material for the clip. The material used for the clip can be chosen to maintain a positive margin between the material's flexural yield strength divided by the safety factor (e.g., 1.25 in the elastic range) and the applied bending stress. This stress can range from 100 to 250 MPa. In this particular case, a material with a flexural strength at its yield strength at 23°C, according to ISO 178, ranging from 125 to 315 MPa can be selected.

[0042] The end of the flexible arm (3a) is preferably beveled (9). This facilitates insertion of the clip into a notch in a flange.

[0043] The clip includes a means to prevent its removal after insertion into one of the flanges. Thus, once inserted into the flange, the clip cannot spontaneously come out. It is secure and cannot be manually removed. This means may be a lug (8) designed to cooperate with a shoulder (10) provided inside the flange. Preferably, the lug is located on the flexible arm (3a) of the clip. The clip is mounted by snapping the lug onto the shoulder (10). The clip can be inserted by an operator without the need for any special tools.

[0044] The keying feature provided by the clip allows the modules to be mechanically assembled by bringing the side surfaces of the flanges into contact in a unique configuration that combines interface compatibility and orientation. This prevents any unwanted electrical connections between two adjacent modules during subsequent wiring. This keying feature is achieved by selecting a first and a second portion of the clip with cross-sections of different shapes or dimensions. Figure 2 shows a bottom view of the clip in Figure 1. The cross-section of the first portion (3) is circular, while the cross-section of the second portion (7) is T-shaped. The cross-sectional shape of the first and second portions of the clip is not limited to a circular or T-shape.Other shapes are possible, such as oval, triangular, square, trapezoidal, or U-shaped, provided that the cross-sectional shape of the first portion differs from that of the second portion. Figure 2 also shows that the heel (200, 201) extends in a direction perpendicular to the direction in which the first and second portions of the clip extend. The heel acts as a stop when inserting the clip into the flanges. will be explained below. Figure 2 also shows the lug (8) which allows one of the arms to snap into the notch of a flange and lock the clip in the flange.

[0045] Figure 1 shows that the surface of the heel intended to face outwards from the module may include an attachment means for passing a tie, which secures one or more electrical wires to the clip. The attachment means may be a bridge (100). The tie may be a plastic cable tie of the Rilsan type passing around or through the bridge. Description of a module and flanges.

[0046] A module is a fixed-volume unit that delivers a predetermined voltage and energy. The available voltage and energy depend on the electrical connection method of the electrochemical cells. These cells are generally arranged regularly around a central axis and connected to each other by metal strips. The central axis serves to secure the cells together and also to mount the module onto a support. This support then holds the various modules of the battery together. The module typically includes an electronic control and management circuit designed to measure the state of charge and / or the health of the cells, notably through individual voltage or current measurements taken on a cell-by-cell basis, or on a group of cells.

[0047] Configurations using 3, 4, or 5 electrochemical cells per module are the most advantageous. The configuration with 4 electrochemical cells is optimal in terms of compactness while meeting mechanical, thermal, and electrical requirements. The size of the electrochemical cells is not particularly limited. They can be cylindrical or prismatic, preferably cylindrical. The technology of the electrochemical cells is also not limited. They can be lithium-ion. They can be primary (non-rechargeable) or secondary (rechargeable).

[0048] The electrochemical elements are held together within a single module using one or more flanges. A single flange can completely or partially surround the side wall of each electrochemical element. It can be positioned near the midpoint of the length (or height) of the electrochemical elements. However, for better element retention, two flanges are preferably used. They are each positioned at one end of the electrochemical elements within the module.

[0049] A flange consists of a plate with multiple recesses across its largest surface, designed to fit into the base of the electrochemical element container and / or the lid of the electrochemical elements. Each recess conforms to the shape of the cross-section of the container or the lid of the electrochemical elements. The cross-section is preferably circular. In addition to its function of assembling the elements within a module, the flange secures the electrochemical elements to prevent them from being damaged by vibrations. The flange is generally made of an electrically insulating material, preferably a plastic. It is usually produced by molding a plastic material. Assembling the flanges of two modules joined together using the clip

[0050] Each flange has a lateral surface defined as the surface perpendicular to the largest surface of the flange. This lateral surface has one or more notches that extend over at least a portion of the height of the lateral surface of the flange and that open onto the largest surface of the flange.

[0051] The joining of two modules causes two notches on the two flanges to come together to form a common groove into which the clip is inserted.

[0052] The electrical connection of two modules in an undesired configuration (keying function) is prevented by placing the lateral surfaces of two flanges opposite each other, each flange having two notches with cross-sections of different shapes or dimensions. The cross-section of the notch on one flange of one of the two modules differs in shape or dimensions from the cross-section of the notch on a flange of the other module placed opposite it.

[0053] The first and second portions of the clip each fit into the notch of one of the two flanges. The clip is inserted either from the top of the module for the flange in the upper position, i.e. covering the upper end of the electrochemical elements, or from the bottom of the module for the flange in the lower position, i.e. covering the lower end of the electrochemical elements.

[0054] The clip performs the keying function because the cross-sectional shape of the first portion of the clip is complementary to that of the cross-sectional shape of the notch in the first flange into which the clip is intended to be inserted. Similarly, the cross-sectional shape of the second portion of the clip is complementary to that of the cross-sectional shape of the notch in the second flange into which the clip is intended to be inserted.

[0055] The lug located on one of the two arms of the clip allows the clip to be locked in position in one of the two flanges.

[0056] In a preferred embodiment, each module comprises four electrochemical elements joined by a square flange, optionally with rounded corners, each of the four sides of the square having a notch. Figure 4 is a bottom view of an assembly (11) of two such modules (2-1, 2-2) joined together and assembled by the clip according to the invention. It shows in particular the different cross-sections of the notches (4-1, 4-2) formed on the lateral surfaces opposite the flanges (5-1, 5-2) of the two modules. Two notches located on opposite sides have different cross-sections. The notch (4-2) of the flange of the left module (2-2) has a T-shaped cross-section. The notch (4-1) of the flange of the right module (2-1) has a circular cross-section.Figure 4 shows that the first portion (3) of the circular cross-section clip fits into the circular cross-section notch (4-1) of the right module flange. The second portion (7) of the T-shaped cross-section clip fits into a T-shaped cross-section notch (4-2) of the left module flange. Each flange can be equipped on its lateral surface with a keying feature in the form of a raised bump (300-2 on flange 5-2 and 300-1 on flange 5-1) so that no 90° error in the orientation of the modules is possible. Other flanges (15-1 and 15-2 in Figures 7 to 11) located at the opposite end of the electrochemical elements can also be provided with this boss positioned at the same corner as these flanges 5-1 and 5-2. The presence of this boss indicates to an operator a unique orientation of the modules.Indeed, without this boss, since each flange has two notches of the same cross-section on two perpendicular sides, an operator would have to choose between two possible flange orientations when aligning a first notch with a given cross-section with a second notch on another flange with a different cross-section. These two orientations differ from each other by a 90° rotation angle around the module's longitudinal axis. The presence of the boss in one corner indicates a single orientation for the flange. The operator can therefore no longer hesitate between the two flange orientations. Figure 4 shows that both modules are oriented so that the bosses are both located in the upper left corner.The flanges defined with their two notches 4-1 and 4-2 arranged opposite each other, if placed on tooling coupled to the notches, guarantee together with the clip's keying, a unique orientation of the modules.

[0057] The heel acts as a stop when inserting the clip into the common groove formed by the alignment of the two notches (4-1, 4-2) of the two flanges.

[0058] One of the advantages of the flange used in the invention is that its lateral surface is devoid of protruding parts, which minimizes the space between two adjacent modules and thus optimizes the compactness of the module assembly.

[0059] Variability is sometimes observed in the distance between the central axes of two modules fixed to a support, a distance also called the center-to-center distance. This variability in the center-to-center distance could create mechanical stresses if a conventional connecting bracket were used to assemble the modules. The invention prevents the formation of these stresses by providing clearance in both the X and Y dimensions of a horizontal plane between the clip and one of the two flanges. Furthermore, variability in the height of the modules is also sometimes observed. This variability can lead to a height difference between the modules after they have been fixed to a support. This height difference could again create stresses if a conventional connecting bracket were used. The invention absorbs these height differences by providing clearance in the vertical direction.The first or second portion of the clip is dimensioned so that there is clearance between this first or second portion and the notch into which it fits. This clearance is present in all three dimensions and thus compensates for variations in the center-to-center distance or height of the modules. The position of one of the two modules may vary slightly in a horizontal plane and in a vertical direction, within the limits imposed by the clearance between the clip portion and the module's flange. The clearance can be at least 0.15 mm and less than 1 mm in each of the three dimensions.

[0060] Figure 3 is a bottom view of the area where two modules meet. It shows, in particular, the clearance (12) in the horizontal XY plane between the second portion (7) of the clip, which has a T-shaped cross-section, and the notch (4-2) in the flange (5-2) into which this portion is inserted. The left flange (5-2), and therefore the left module, is slightly mobile in the horizontal XY plane and in the vertical direction due to the presence of this clearance. The right flange (5-1), and therefore the right module, is fixed because there is no clearance in the horizontal plane or in the vertical direction between the first portion (3) of the clip and the flange (5-1).

[0061] The clip can be snapped into place from the top of a flange covering the upper end of the module's electrochemical elements or from the bottom of a flange covering the lower end of the module's electrochemical elements. Figure 5a shows a longitudinal cross-sectional view of a clip (1H) joining two flanges (15-1, 15-2) located at the upper end of two modules. Figure 5b shows a longitudinal cross-sectional view of a clip (1B) joining two flanges (5-1, 5-2) located at the lower end of two modules. In both figures, the presence of a A gap (12) in the vertical direction Z-Z' between the clip's heel (201) and the inner wall of the flange allows the left flange (5-2), and therefore the left module, to move slightly in the vertical direction. The left module is thus slightly mobile relative to the clip, while the right module is fixed relative to the clip. The clip allows for the assembly of two modules while permitting some variation in module height.

[0062] One of the advantages of the clip is that once inserted between two flanges, it cannot dislodge spontaneously. This is because one of the two portions of the clip has a lug (8) that is pressed against a shoulder (10) of the flange, preventing any upward vertical movement of the clip relative to that flange. Furthermore, the clip's heel acts as a stop, preventing any downward vertical movement of the clip. The clip can, however, be removed after being drilled.

[0063] Using a single clip on only one end of the electrochemical elements does not allow for a permanent assembly of the modules. Indeed, in the case of a single connecting element, for example at the upper end of the elements, it is possible to remove the module located on the side of the clip portion without the tab by sliding the module downwards. Using a second clip on the opposite end of the electrochemical elements allows for a permanent assembly of the two modules. Figure 6 shows an assembly (11) of two modules (2-1, 2-2). Each module results from the combination and electrical connection of several electrochemical elements (6-1, 6-2). Each module has an upper flange (15-1, 15-2) and a lower flange (5-1, 5-2). The two modules are assembled by their upper flanges (15-1, 15-2) by means of an upper clip (1 H) and by their lower flanges (5-1, 5-2) by means of a lower clip (1 B).Note that the left module (2-2) cannot be separated from the right module (2-1) because it is blocked by the heel (201) and the lug (8) of the second clip (1 B) located on the lower part of the two modules.

[0064] Figures 7 to 11 show, in chronological order, different stages of the assembly of four modules (2-1, 2-2, 2-3, 2-4), each comprising four electrochemical elements. Each module has an upper flange (15-1, 15-2, 15-3, 15-4) and a lower flange (5-1, 5-2, 5-3, 5-4). In Figure 7, two modules (2-1, 2-2) are placed side by side. The modules are oriented so that the cross-section of the cutout in one of the notches (4-1) is different from the cross-section of the cutout in the opposite notch (4-2). A first clip (1H) and a second clip (1B) are inserted into the two upper and two lower flanges, respectively, thus assembling the two modules. In Figure 8, a third module (2-3) is attached to the first module (2-1). The assembly of the 3 ème The module is made by inserting a clip between the upper flange (15-1) of the 1 er module (2-1) and the upper flange (15-3) of the 3 ème module. Two clips (1 B) are inserted into the lower flanges of the second and third modules in anticipation of the addition of a 4 ème module. In figure 9, a fourth module (2-4) is inserted onto the two clips located on the lower flanges (5-2, 5-3) of the 2 ème and of the 3 ème In Figure 10, two additional clips (1 H) are inserted respectively between the upper flanges (15-2, 15-4) of the second and fourth modules and between the upper flanges (15-3, 15-4) of the third and fourth modules. Figure 11 shows the four modules assembled after the insertion of these last two clips (1 H).

Claims

Demands

1. Connecting piece (1) for joining two battery modules (2-1, 2-2), said connecting piece comprising: - a first portion (3) adapted to fit into a notch (4-1) of a first retaining element (5-1) of a first plurality of electrochemical elements (6-1) forming part of a first battery module (2-1) and - a second portion (7) suitable for fitting into a notch (4-2) of a second retaining element (5-2) of a second plurality of electrochemical elements (6-2) forming part of a second battery module (2-2), the first portion and the second portion having different dimensions, such that the first portion is not suitable for fitting into the notch of the second retaining element and / or the second portion is not suitable for fitting into the notch of the first retaining element, - a means (8) to prevent the removal of the connecting piece after its insertion into a notch of one of the two retaining elements.

2. Connecting piece (1) according to claim 1, made of a non-current conductive material, such as plastic.

3. Connecting piece (1) according to claim 1 or 2, wherein the first portion (3) comprises a hand-flexible part (3a) and a hand-non-flexible part (3b), the hand-flexible part and the hand-non-flexible part forming respectively a first and a second branch, the first and second branches being at least partially disjointed, thus allowing deformation of the hand-flexible part relative to the hand-non-flexible part.

4. Connecting piece (1) according to claim 3, wherein the material constituting the connecting piece has a flexural strength at the yield strength at 23°C according to ISO standard ranging from 125 to 315 MPa.

5. Connecting piece (1) according to any one of claims 1 to 4, wherein a cross-section of the first portion (3) is circular or semi-circular or oval or semi-oval in shape and a cross-section of the second portion (7) is T-shaped.

6. Connecting piece (1) according to any one of claims 3 to 5, wherein a free end of the flexible part (3a) is hand-beveled (9).

7. Connecting piece (1) according to any one of claims 3 to 6, wherein the means for preventing removal of the connecting piece is a lug (8) located on the hand flexible part (3a), adapted to snap against a shoulder (10) of one of the retaining elements (5-1, 5-2).

8. Set (11) comprising: - a first battery module (2-1) equipped with at least one first retaining element (5-1) used to retain a first plurality of electrochemical elements (6-1) and a second battery module (2-2) equipped with at least one second retaining element (5-2) used to retain a second plurality of electrochemical elements (6-2), - a connecting piece (1B) according to any one of claims 1 to 7, assembling the first retaining element (5-1) with the second retaining element (5-2), the first portion (3) fitting into a notch (4-1) of the first retaining element (5-1) and the second portion (7) fitting into a notch (4-2) of the second retaining element (5-2), the first portion being configured so as not to be able to fit into the notch (4-2) of the second retaining element and / or the second portion being configured so as not to be able to fit into the notch (4-1) of the first retaining element, of play (12) being present between the first or the second portion of the connecting piece and the notch into which the first or the second portion fits, this play allowing a displacement of one of the two battery modules relative to the other, in the three dimensions of space.

9. Assembly according to claim 8, wherein the gap (12) is at least 0.15 mm and less than 1 mm in each of the three dimensions of space.

10. Assembly according to claim 8 or 9, wherein the notch (4-1) of the first retaining element (5-1) has at least one different dimension from the notch (4-2) of the second retaining element (5-2).

11. Assembly according to any one of claims 8 to 10, wherein the notch (4-1) of the first retaining element (5-1) and the notch (4-2) of the second retaining element (5-2) extend along the longitudinal direction of the electrochemical elements, the shape of the cross-section of the notch (4-1) of the first retaining element being different from the shape of the cross-section of the notch (4-2) of the second retaining element.

12. Assembly according to claim 11, wherein the cross-section of the notch (4-1) of the first retaining element (5-1) has a circular or semi-circular or oval or semi-oval shape and the cross-section of the notch (4-2) of the second retaining element (5-2) is T-shaped.

13. Assembly according to any one of claims 8 to 12, wherein: - the first (5-1) and second (5-2) retaining elements cover a first end of the first plurality (6-1) and second plurality (6-2) of electrochemical elements respectively, - the first connecting piece (1 B) connects the first and second retaining elements located at the same first end of the electrochemical elements, the assembly further comprising: - a first (15-1) and a second (15-2) second-end retaining element covering the opposite end of the first and second plurality of electrochemical elements respectively, - a second connecting piece (1 H) linking the first and second retaining element of the second end, the second connecting piece being according to one of claims 1 to 7.

14. Assembly according to claim 13, wherein the first (1B) and the second (1H) connecting piece each have a heel (200, 201) preventing the separation of the first (2-1) and the second (2-2) battery module.

15. Assembly according to claim 13 or 14, wherein the first (2-1) and the second (2-2) battery module each contain four electrochemical elements, the retaining elements (5-1, 5-2) being square in shape, with optionally rounded corners, the four sides of the square each receiving a notch (4-1, 4-2).

16. Assembly according to claim 15, wherein two notches (4-1, 4-2) located on two opposite sides of the square have different dimensions and shapes.

17. Battery comprising at least one set according to any one of claims 8

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